U.S. Pat. No. 5,711,777 (Nickey et al.), which is assigned to the assignee of this application, the disclosure of which is incorporated by reference herein, discloses shearing apparatus for shearing gobs of molten glass from each of a plurality of spaced apart, downwardly flowing streams of molten glass. The '777 patent utilizes a plurality of individual blades, one for each of the glass streams to be sheared, on each of an opposed pair of carriages, and drive means for moving the carriages periodically toward one another to bring the opposed pair of shear blades into partly overlapping, shearing relationship with one another, and then away from one another to permit a portion of the molten glass stream to be sheared by such opposed pair of blades to pass therebetween until sufficient molten glass has passed therebetween to form another gob. The '777 patent specificatively discloses three (3) such shear blades on each of the opposed pair of carriages, along parallel or substantially parallel paths which is the arrangement to be used in simultaneously shearing glass gobs from each of three (3) spaced apart, downwardly flowing streams of molten glass, a process that is used in producing glass containers by the triple gob version of a glass container forming machine of the individual section (I.S.) type. Of course, only two (2) such shear blades would be used in producing glass containers by a double gob version of an I.S. machine, and four (4) such blades would be required in producing glass containers by a quadruple gob ("quad") version of such a machine. Other prior art versions of an opposed carriage, multiple glass gob shearing apparatus are disclosed in U.S. Pat. Nos. 4,450,741 (Mumford) and 4,499,806 (Mumford), the disclosure of each of which is also incorporated by reference herein.
The shearing devices described in each of the aforesaid '777, '741 and '806 patents utilize individual shear blades on each of the opposed, reversible motion carriages, one (1) such shear blade each of the carriages for each of the glass streams to be severed. Thus, each such blade must be individually installed on its carriage, and individually removed from such carriage when it is time for resharpening or replacement, which occurs quite frequently in a high production glass container manufacturing operation, and these are time consuming procedures and necessitate a suspension of container production during the installation and removal steps. Also, in such an arrangement individual shear blades are subject to warpage during service due to a high temperature environment in which they are used, and this warpage can vary from blade to blade of the blades on each carriage, which can lead to shear marks on the sheared gobs and on the containers formed therefrom, and/or to premature blade wear due to the abrasive character of molten glass.